(1) Field
The disclosed methods and systems relate generally to power systems, and more particularly to multiple transformer configurations.
(2) Description of Relevant Art
A common problem in situations involving power system transformer failure is that there is typically a short time lag between the time the main transformer has ceased operation, and the time the back-up transformer, if one is installed, begins operations and allows the power system to resume regular operation. Such a time lag, even if relatively short, and the resultant power interruption to power-consuming devices connected to the power system via the failed transformer could cause sensitive power devices to shut down, thereby resulting in potentially serious economic damage to consumers affected by the power disruption and the ensuing shut down of economically critical power applications. For instance, electrically powered chemical refineries, paper mills, and other similar operations, could suffer economic harm by a power disruption caused by a failed transformer. Additionally, it often becomes necessary to take a transformer off-line for necessary maintenance work. Under these circumstances, a power disruption to consumers, even if a back-up transformer is ready to assume operation, is often inevitable, and could also result in economic harm.
One possible way to address these types of power disruptions is to connect the power-consuming devices to two or more independent power sources. However, such a solution may not be feasible due to expensive overhead necessitated by the connection of two or more power sources, and the accompanying apparatus (e.g., power lines, transformers, etc.). Moreover, such a solution also entails considerable power waste since more power is available to the power-consuming devices than is generally required. Another solution then is to connect two, or more, transformers to the power source supplying power to the power-consuming devices, so that the two, or more, transformers can operate in tandem and thus provide back-up or redundancy to the power system. Although this solution appears to be satisfactory and simple, tandem operation of two or more transformer has been unsatisfactory due to the tendency of multiple transformers used conjunctively to compete with each other for the power supplied by the power source. Consequently, competing transformers cause the power system to become unstable as the voltage levels at the output of the transformers feeding the power consuming devices fluctuate.